Surgical retractor

ABSTRACT

This surgical retractor has a pair of opposed slat-like sides interconnected at their respective ends with divergence at both ends so that the slats are elastically bowed in arcuate paths with the concave sides of the slats facing each other. Each of the slats has cooperating ratchet and pawl arrangements to permit substantially free lengthwise extension and restricted lengthwise retraction. In one embodiment, the slats are pivotally interconnected at their ends with a ratchet arrangement that permits increase in divergence of the slats and restricts decrease in divergence. In another embodiment, the slats are elastically interconnected at their ends. Extension pieces may be used for varying the size of retractor. An illuminator may be mounted on the retractor as a transparent flexible sterilizable sleeve for surrounding a flexible fiber optic bundle thereby providing illumination from a remote light source. Preferably, the retractor is formed of plastic for disposal after use.

United States Patent [1 1 Apr. 30, 1974 McDonald SURGICAL RETRACTOR [76] inventor: Bernard McDonald, 18212 Pacific Coast Hwy., Malibu, Calif. 90265 [22] Filed: Mar. 1, 1972 [21] Appl. No.: 230,799 g Primary ExaminerLucie H. Laudenslager Attorney, Agent, or Firm-Christie, Parker & Hale '[57] ABSTRACT This surgical retractor has a pair of opposed slat-like sides interconnected at their respective ends with divergence at both ends so that the slats are elastically bowed in arcuate paths with the concave sides of the slats facing each other. Each of the slats has cooperating ratchet and pawl arrangements to permit substantially free lengthwise extension and restricted lengthwise retraction. In one embodiment, the slats are pivotally interconnected at their ends with a ratchet arrangement that permits increase in divergence of the slats and restricts decrease in divergence. In another embodiment, the slats are elastically interconnected at their ends. Extension pieces may be used for varying the size of retractor. An illuminator may be mounted on the retractor as a transparent flexible sterilizable sleeve for surrounding a flexible fiber optic bundle thereby providing illumination from a remote light source. Preferably, the retractor is formed of plastic for disposal after use.

12 Claims, 8 Drawing Figures PATENTEDAPRSO m4 sit-307L393 SHEET 3 OF SURGICAL RETRACTOR BACKGROUND OF THE INVENTION Surgical retractors are used for spreading apart or separating the walls of nartual body orifices or for spreading the margins of surgical incisions. With the edges ,of an incision spread apart, the surgeon has access to the underlying tissues or-organs permitting .a clear view of the surgical site and access for a desired surgical or medical treatment. Thus, for example, an abdominal retractor may be used in an abdominal incision to hold back the skin, subcutaneous fat and the internal peritoneal wall for ready access to the many abdominal organs.

In the past, a variety of surgical retractors have been employed. Hand retractors are typically steel instruments with a broad hook-like flap at one end for fitting over the tissue to be retracted. These are then pulled apart by hand and may be held or clamped during the surgical procedure. Some surgical retractors have arms that are interconnected by a gear or rack and pinion arrangement so that they can be cranked apart and locked in position. Another surgical retractor has four pivotally connected, rigid, curved links which can be clamped in any desired position to hold an incision open. Still another surgical retractor has a rigid peripheral ring with multiple detachable and movable blades that can be clamped at any point on the ring to hold a surgical site open.

Typically, such instruments have been made of stainless steel so as to be sterilizable between surgical procedures. The instruments are relatively heavy and stout because, in some cases, substantial forces may be involved in opening anv incision and keeping it open. Since specially made, the instruments are expensive and it is costly to repetitively sterilize them and maintain sterility for surgery. Some of the more complicated retractors need to be taken apart for cleaning after surgery and reassembled before use.

It is desirable to provide a retractor that is sufficiently inexpensive that it can be disposed of after'a single use thereby obviating cleaning and sterilization between uses. Such an instrument should be simple, rugged and versatile.

BRIEF SUMMARY OF THE INVENTION There is, therefore, provided in practice of this invention according to a presently preferred embodient a surgical retractor having a pair of elongated elastic slats interconnected at their respective ends with divergence at each end so that the slats elastically bow in arcuate paths therebetween. Ratchet means are provided for freely extending the length of the slats and resistin longitudinal contraction thereof.

DRAWINGS These and other features and advantages of the present invention will be appreciated as the same becomes better understood by reference to the following detailed description of a presently preferred embodiment when considered in connection with the accompanying drawings wherein:

FIG. 1 illustrates in a general plan view a surgical retractor constructed according to principles of this invention;

FIG. 2 is a detailed plan view of one end of the retractor ofFlG. 1;

FIG. 3 is a side view, partially cut away on line 3-3 of FIG. '2, of the end of the retractor;

FIG. 4 is a transverse cross section of one extendible side arm of the retractor of FIG. 1 taken on line 4-4 of FIG. 1;

FIG. 5 is a side view of a female portion of the side arm;

FIG. 6 is a side view of a male portion of the side arm;

FIG. 7 is a fragmentary longitudinal cross section of the female member taken on line 7-7 of FIG. 5;

FIG. 8 is a plan view of another embodiment of ratchet at and end connection of a surgical retractor;

- FIG. 9 is a plan view of another embodiment of retractor constructed according to principles of this invention;

FIG. 10 illustrates in side view an extender piece for a surgical retractor; 7

FIG. 11 illustrates an illuminator mounted on a surgical retractor; and

FIG. 12 illustrates the end of the illuminator.

DESCRIPTION FIG. 1 illustrates in general plan view a surgical retractor constructed according to principles of this invention. As illustrated in this drawing many of the details, particularly the end ratchets, are omitted since shown in substantial detail in subsequent drawings. Broadly, the retractor of FIG. 1 comprises a pair of similar, elastically bendable slats 15 pivotally interconnected at their ends. Each of the side slats 15 has a male member 16 mated with a female member 17, each of which is described in greater detail hereinafter. The male and female members are slidably engaged for length-wise extension and contraction of the combined side slats 15. Each of the female members 17 is formed as an extension from a cylindrical hinge half 18 seen in greater detail in FIGS. 2 and 3. The other hinge half 19 (FIG. 3, hidden in FIG. 1) is'connected to the malemember 16. A hinge pin 21 formed integral with the lower hinge half 19 holds the two hinge halves together and permits pivotal movement at each end of the surgical retractor. For ease of assembly of the two hinge halves 18 and 19, it is convenient to provide a slightly enlarged head 22on the hinge pin 21. A pair of intersecting longitudinal slits 23 through the head 22 and at least a portion of the hinge pin 21 permits the hinge pin to collapse part away as the upper hinge half 18 is pressed on. When the upper hinge half is pressed on to its full extent, the hinge pin snaps back out and the head 22 prevents the two parts from coming apart again. Thus, by siinply pressing the two halves of the hinge together, it can be assembled without any detachable fasteners.

As seen in greater detail in FIGS. 2 and 3, the pivot at each end of the surgical retractor is also provided with a ratchet for free rotation of the pivot to permit the male and female members to freely increase divergence and restrict decreae in divergence thereof. Recessed into the upper face of the lower hinge half 19 is an annular array of radially extending ratchet teeth 24. As will be apparent, the surgical retractor is typically opened (increasing divergence of the slats) to only a limited extent during use and therefore the ratchet teeth 24 need extend only a portion of the way around the lower hinge half 19.

An aperture 26 extends through the upper hinge half 18 opposite the row of ratchet teeth 24. A pawl 27 extends through the aperture 26 and engages the ratchet teeth 24. The pawl 27 is an end portion on a short lever 28 mounted on the upper face of the upper hinge half by a pair of spaced apart bosses 29. A pin 31 extending between the bosses supports the lever near its middle. A somewhat enlarged thumb pad 32 at the opposite end of the lever from the pawl 27 enables one to lift the pawl from engagement with the ratchet teeth for releasing the ratchet when desired. A coil spring 33 beneath the thumb pad 32 rests in a recess 34 in the combined upper hinge half 18 and male member 17. Preferably, a pin 36 on the bottom side of the lever 28 fits within the spring 33 to assure that it is always captive and cannot become lost in a surgical site.

Thus, the hinges between the male and female members at each end of the surgical retractor and the ratchet and pawl arrangement permit the side slats of the surgical retractor to relatively freely be increased in divergence since the pawl merely clicks along the ratchet teeth. One merely pulls on the side slats to open the retractor. A decrease in divergence of the side slats is restricted when the pawl engages the ratchet teeth. If it is desired to release the ratchet, the thumb pad is pressed, disengaging the pawl from the teeth and the divergence of the side slats can then decrease.

FIG. 4 is a transverse cross section of one of the side slats in the portion where the male and female members l6 and 17, respectively, are engaged. The female member 17 has a curved web 38 forming its principal vertical extent. On its inner or concave side, that is, the side facing the other side slat 15 (FIG. 1) of the surgical retractor, the female member has raised lip 39 along the top and bottom edges. On its outside face, the female member has a pair of hook-like flanges 41 extending along the length. Very broadly, the female member thus has a transverse cross section somewhat like an I- beam.

The male member 16 also has a curved web 43 extending as the principle portion of its height. The curvature of the two webs 38 and 43 is such that they bow apart from each other. The opposite edges of the web 43 fit into the re-entrant channel formed by the hookshaped flanges 41 on the female member. Thus, the male member is kept captive in a transverse direction but is free to slide in a longitudinal direction along the female member. A pair of ribs 44 extend outwardly from the web 43 along the length of the male member. The ribs 44 are spaced a short distance apart from the edges of the web 43 so as to clear the tips of the hookshaped flanges 41. Thus, the male member has a transverse cross section somewhat in the shape of a bench or Greek letter pi.

A series of ratchet teeth 46 extend along the length of the inside of the web 43 on the male member, as best seen in FIG. 5, which is a side view of the inner face of one end of the male member. Two or three pawl teeth 47 are provided on the outer face of the web 38 on the female member as may be seen in FIGS. 6 and 7, which comprise a view of the outer face of an end of the female member and a fragmentary longitudinal cross section thereof, respectively.

As best seen in FIG. 4, the pawl teeth 47 engage the ratchet teeth 46 between the webs 38 and 43 of the female and male members. The teeth of the ratchet and pawl are oriented to permit motion in a direction tending to extend the length of the side slat 15 formed of the combined male and female members. The teeth inhibit or restrict lengthwise contraction of the side slat. The pawl teeth can ride over the ratchet teeth due to elastic deformation of the webs 38 and 43 as cammed apart by the teeth.

When it is desired to release the ratchet and pawl arrangement thus provided, one need only pinch the female member at its side edges adjacent the flanges 41. Such pinching causes the curved webs to bend further and be spaced apart a greater distance at their mid section thereby disengaging the pawl teeth from the ratchet teeth and permitting the side slats to be contracted in a lengthwise direction.

In order to use the surgical retractor in, say, an abdominal incision, the incision is made and the retractor inserted in a contracted state. Typically, the male and female members are substantially straight or only slightly curved when made and when inserted into the incision. The side slats thus are close to each other when the retractor is inserted. The flesh to be retracted fits between the two ribs 44 on the male member along part of the slat length and the flanges 41 on the female member along the rest of the slat length and is, hence, held substantially captive in the channels adjacent the webs 43 and 38. Referring to FIG. 3, ribs 48 are.provided on the hinge halves substantially as extensions of the aforementioned ribs and flanges for retaining the flesh to be retracted at the ends of the retractor.

After positioning the retractor in the incision, the two side slats are manually spread apart thereby activating the ratchet and pawl arrangement at the hinges at each end of the retractor. As the slats diverge adjacent their ends lengthening they are spread apart, they elastically bend along their length in a plane transverse to the webs. This elastic bowing of the side slats forms a double curved opening between the sides of the retractor approximately as shown in FIG. 1. In addition to increasing divergence of the side slats, their length may also be increased merely by pulling the two end portions of the surgical retractor away from each other. This activates the ratchet and pawl arrangement between the male and female members and permits longitudinal extension of the side slats. Such longitudinal extension may be employed for legthening the available surgical site or may merely provide the additional length required as the side slats are bowed apart. It will be noted that as the stresses due to tissue being retracted increase as the surgical site is opened, the curvature of the side slats typically increases as well thereby strengthening the slats against buckling. Since both the angle at the end of the slats and the length of the slats is adjustable, the retractor is quite versatile and may be used in long narrow openings or short wide ones.

When it is desired to close the surgical site, the retractor can be collapsed quite readily. The length of the side slats is decreased by pinching the upper and lower edges of the side slats adjacent the pawl teeth towards each other thereby further bowing the webs 38 and 43 and disengaging the pawl teeth 47 from the ratchet teeth 46. The male member can then slide into the female member freely for contracting the side slats. The ratchets at the ends of the retractor are released simply by pressing the thumb pad 32 on the lever 28 thereby disengaging the pawl 27 from the ratchet teeth 24. This permits the divergence of the side slats to decrease.

Since the two ends of the surgical retractor are identical, a pair of identical male members and their integral hinge halves and a pair of female members with their integral hinge halves are snapped together to form the surgical retractor. These parts are preferably made by die casting or rubber mold casting of any of a variety of modern plastic on synthetic materials which have already come into wide use in hospitals and other medical practice. Many such materials are readily sterilizable at the time of manufacture and assembly and are then individually packaged, not to be opened until re- I quired for surgery. Since such retractors can be made economically, they can be used once and then discarded, thereby obviating cleaning and resterilization.

The choice of plastic materials is also advantageous in providing an appropriate degree of elastic bowing of the side slats when the retractor is used. The shapes of the male and female members forming the side slats are such that substantial changes in section modulus can be made without substantial changes in the overall dimensions of the side slats. If desired, steel strips can be imbedded in the plastic for controlled stiffness and strength. With such possible variations, retractors for symmetrical or asymmetrical openings of surgical sites canreadily be provided, and substantial changes in size and the stiffness of the surgical retractor can be made in the course of designfor particular applications.

FIG. 8 illustrates in plan view another embodiment of end ratchet for an elastic surgical retractor as provided in practice of this invention. As illustrated in this embodiment, there are no teeth on the ratchet and continuous adjustment of the width of the surgical site is provided. A female member 51 of an elastically bendable and extensible side slat is formed integral with an upper hinge half 52.'A male member 53 of the opposing side slat is integral with a lower hinge half which is hidden beneath the upper hinge half 52 in FIG. 8. A hinge pin 54 integral with the lower hinge half extends upwardly through the upper hinge half and ends in a split head 56, which keeps the two hinge halves together. At least a portion 57 of the upper hinge half 52 is cylindrical and coaxial with the hinge pin 54. l i

A pivot pin 59 also extends upwardly from the lower hinge half and provides mounting for an eccentric cam 60. A spring 61 between the side slat 53 and the cam 60 urges the cam in a clockwise direction as seen in FIG. 8. A release lever 62 extends from the cam for thumb or finger pressure for turning the cam in a counterclockwise direction. When the retractor is used, the two side slats 51 and 53 are spread apart manually as hereinabove described, thereby causing the cylindrical surface 57 on the upper hinge half to ride along on the eccentric cam 60 and friction therebetween tends to disengage the cam from the cylindrical surface. When the slats are released, however, the spring 61 and any friction with the cylindrical surface 57 urge the cam in a clockwise direction and into wedging engagement with the cylindrical surface. This wedging action effectively prevents the side slats from collapsing towards each other until the release lever 62 is pressed to disengage the eccentric cam from the cylindrical surface. Continuous motion of this toothless ratchet is thereby provided. If desired small teeth or minor roughness may be provided on the cam 0r hinge or both to inhibit slippage in case the camming surfaces become lubricated by fluids during surgery.

- FIG. 9 illustrates in plan view another embodiment of surgical retractor constructed according to principles of this invention. As illustrated in this embodiment, the elastically bendable and freely extensible side slats are each formed of a pair of extension pieces 66. At each end of the surgical retractor, there is a somewhat V- shaped end piece 67 so that the retractor has the same general elongated outline as that hereinabove described and illustrated in FIG. 1. The elastically bent side pieces are interconnected by the end pieces 67 which are also elastic but with a somewhat higher section modulus adjacent the tip of the V to maintain the desired shape.

Each of the side slat pieces 66 has a male cross section for about half its length and a female cross section for about half its length. A side view of one of the side slats 66 is seen in FIG. 10. One end 71 has a male cross section and the other end 72 has a female cross section substantially the same as those illustrated in the transverse cross section of FIG. 4. The male half 71 thus has a pair of parallel ribs 44 extending along its length. Near the mid point, these ribs are gradually converted to side flanges 41' on the female end. A few pawl teeth 47' are provided on the outside face of the web 38' of the female end. Similarly, a row of ratchet teeth 46' are provided on the opposite face of the web 43' of the male end. Thus, when two such side slat pieces are assembled end to end, the pawl teeth of one engage the ratchet teeth of the next.

A pair of stop teeth 73 are provided on the web 38 of the female member and a corresponding pair of stop teeth 74 are provided on the web 43 of the male member. These teeth 73 and 74 face oppositely to the ratchet and paw] teeth. This permits the male end of one extension piece to, be inserted into the female end of another extension piece, however, it limits the extent of withdrawal of the two parts so that over-extension of the side slats is avoided. This is typically of no problem in an embodiment as illustrated in FIG. 1 where the entire extension of the side slats occurs in a single ratchet and pawl assembly. In an embodiment as illustrated in FIG. 9, however, a portion of the extension may occur in each of three ratchet and pawl combinations. It could occur that one of these combinations could be overextended inadvertently and the stop teeth are employed to prevent this from happening.

It will be'apparent that an extension piece 66 may be employed in each side slat of a retractor as hereinabove described and illustrated in FIG. 1 in order to obtain a greater length. This can be provided simply by separating each of the illustrated side slats 15 and inserting an extension piece having half male and half female cross sections between the separated ends.

FIGS. 11 and 12 illustrate a means for illuminating a surgical site in combination with a retractor as provided in practice of this invention. It will be apparent, however, that the surgical illumination so provided can be employed with other surgical retractors or similar arrangements adjacent a surgical site. As illustrated in this embodiment, the female portion 17 of a side slat has the illuminator mounted thereon. A plastic clip 76 is snapped onto the flange 41 and lip 39 at thetop edge of the retractor. The clip is sufficiently elastically flexible that its lower hook-like legs 77 at each side can spring over the flange and lip for easy installation and tight gripping. A hollow spherical socket on the top portion of the clip accommodates a ball 78 which readily snaps into the socket to permit free rotation and tilting through a substantial angle. If desired, the ball may be partially split or the clip adjacent the socket may be partially split to assist in insertion of the ball into the spherical cavity. The ball is preferably slightly larger than the cavity so as to be tightly gripped. The friction between the socket and the ball holds the assembly in any position in which it is placed.

A pair of cooperating fingers 79 on the top of the ball define a cylindrical space therebetween into which a fiber optic bundle 81 is snapped. A thin, flexible transparent plastic sheath 82 surrounds the fiber optic bundle so that only the clip and sheath need be sterilized in order to bring the fiber optic bundle into the surgical site, that is, the fiber optic bundle itself need not be sterilized since it is isolated from the site by the sterilizable sheath. The end of the fiber optic bundle is adjacent a conventional light source 83 which can be a great distance from the surgical site.

The other end of the fiber optic bundle which is illustrated in FIG. 12 terminates at the transparent end 84 of the plastic sheath. In this way, the fiber optic bundle is adjustably fixed to a surgical retractor which is typically mounted in the surgical site. The fiber optic light source is fixed in position but, because of the flexibility of the end of the bundle, it can be manipulated and directed to any desired location within the surgical site for either illumination or observation or, if desired, the

bundle may be used for transmission of an intense light beam for pinpoint cauterization. Illumination or observation occurs through the transparent end 84 of the sterilizable plastic sheath 82.

The fiber optic bundle 81 is a conventional item made up of a large plurality of glass or plastic fibers having carefully controlled variations in index of refraction. Because of this, light entering one end of a fiber within the bundle is repetitively reflected along the length of the bundle despite curving thereof and is projected from the other end of the bundle. Since a large number of fibers are used in a bundle, excellent flexibility can be obtained. Illumination of a surgical site by a fiber optic bundle from a remote light source is quite advantageous in modern surgery. Most light sources generate a large amount of heat and by transmitting the light through a fiber optic bundle to the surgical site, the heat can be dissipated at the remote light source without any danger of burning the patient. The removal of the electrical hazard from the proximity of the patient or surgical personnel is also of significant importance, not only in eliminating shock hazard but also in avoiding explosion hazards with some anaesthet- Although limited embodiments, of surgical retractor constructed according to principles of this invention have been described an illustrsted herein, many modifications and variations will be apparent to one skilled in the art. Clearly, many ratchet and pawl arrangements can be adapted to a retractor having elastically bendable and extensible side slats. A variety of modifications in other aspects of the detailed structure will be apparent to one skilled in the art. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise that as specifically described.

What is claimed is:

l. A surgical retractor comprising:

a first elongated elastic slat;

a second elongated elastic slat facing the first slat;

means for connecting each end of the first slat to the respective end of the second slat with mutual divergence of the two slats at each end so that the slats elastically bow in mutually spaced apart arcuate paths between their ends with the concave sides of the slats facing each other; and wherein each slat comprises a pair of interengaging side pieces slidable lengthwise relative to each other, each comprising a curved transverse web, the two webs having their concave sides facing each other; and

ratchet means for freely extending the length of the first and second slats and resisting contraction thereof comprising a plurality of teeth spaced along the length near the center part of the concave side of one web and pawl means comprising at least one tooth near the center part of the concave side of the other web for engaging the ratchet teeth for substantially free lengthwise extension and restricted lengthwise contraction.

2. A surgical retractor as defined in claim 1 wherein one of the side pieces comprises a pair of opposed hook-like flanges extending lengthwise along the side edges on the concave side of the lip and wherein the web of the other side piece fits between the flanges.

3. A surgical retractor as defined in claim 1 wherein each of the side slats includes a pair of spaced apart ribs extending along the length thereof for forming a channel for receiving tissueadjacent a surgical incision or the like.

4. A surgical retractor comprising:

a first elongated elastic slat;

a second elongated elastic slat facing the first slat;

ratchet means for freely extending the length of the first and second slats and resisting contraction thereof;

a pivot for connecting each end of the first slat to the respective end of the second slat with mutual divergence of the two slats at each end so that the slats elastically bow in mutually spaced apart arcuate paths between their ends with the concave sides of the slats facing each other; and

ratchet means for permitting the slats to pivot away from each other and restricting pivoting towards each other.

5. A surgical retractor comprising:

a first elongated elastic slat;

a second elongated elastic slat facing the first slat;

ratchet means for freely extending the length of the first and second slats and resisting contraction thereof;

a pivot connecting each end of the first slat to the respective end of the second slat with mutual divergence of the two slats at each end so that the slats elastically bow in mutually spaced apart arcuate paths between their ends with the concave sides of the slats facing each other; and

ratchet means for permitting the slats to pivot away from each other and restricting pivoting towards each other; and wherein each pivot comprises;

a first hinge half integral with one slat;

a second hinge half integral with the other slat; and

a pin for interconnecting the two hinge halves in pivoting engagement; and wherein the ratchet means comprises:

an annular array of radially extending ratchet teeth on the face of one hinge half; and

a tooth engaging pawl on the other hinge half.

6. A surgical retractor comprising:

a first elongated elastically bendable slat;

a second elongated elastically bendable slat facing the first slat;

pivot means connecting each end of the first slat to the respective end of the second slat for pivoting the slats between a contracted position with the faces of the slats in relatively close proximity and an expanded position with the faces of the slats relatively spaced apart; and a ratchet means associated with each pivot means for permitting the slats to pivot away from each other and restricting pivoting towards each other so that the slats elastically bow in mutually spaced apart arcuate paths between their ends with the concave sides of the slats facing each other.

7. A surgical retractor as defined in claim 6 wherein each ratchet means comprises:

an annular array of ratchet teeth connected to one slat and extending at least part way around the pivot means;

a pawl connected to the other slat and engaging the ratchet teeth; and

means for disengaging the pawl from the teeth for permitting the slats to pivot towards each other.

8. A surgical retractor as defined in claim 6 wherein each of the elastic side slats is freely extensible in a longitudinal direction and includes means for limiting contraction in a lengthwise direction independent of the angle of the pivot.

9. A surgical retractor as defined in claim 8 wherein each of the elastic side slats comprises:

a female member connected to one pivot means;

a male member connected to the other pivot means and inserted into the female member, said male member being substantially free to withdraw from the female member in a longitudinal direction and being restricted from further insertion in the female member.

10. A surgical retractor as defined in claim 9 wherein the male and female members each include a bowed transverse web with respective concave faces thereof facing each other and interengaging ratchet means on the webs for permitting extension and limiting contraction and arranged so that further bowing of the webs disengages the ratchet means.

11. A surgical retractor comprising:

a first arm;

a second arm;

first pivot means for pivotally interconnecting the first and second arms at one end;

first ratchet means for permitting the arms to pivot away from each other and restrict pivoting of the arms towards each other;

a third arm connected as an extension of the first arm away from the first ratchet means;

means for freely extending the combined length of the first and third arms and resisting contraction of the combined length thereof;

a fourth arm connected as an extension of the second arm away from the first ratchet means;

means for freely extending the combined length of the second and fourth arms and resisting contraction of the combined length thereof; second pivot means for pivotally interconnecting the third and fourth arms at the ends thereof opposite from the first and second arms respectively; and

second ratchet means for permitting the third and fourth arms to pivot away from each other and inhibit pivoting of the third and fourth arms towards each other.

12. A surgical retractor as defined in claim 11 wherein each of the arms is elastically bendable in a plane transverse to the axes of the pivot means. 

1. A surgical retractor comprising: a first elongated elastic slat; a second elongated elastic slat facing the first slat; means for connecting each end of the first slat to the respective end of the second slat with mutual divergence of the two slats at each end so that the slats elastically bow in mutually spaced apart arcuate paths between their ends with the concave sides of the slats facing each other; and wherein each slat comprises a pair of interengaging side pieces slidable lengthwise relative to each other, each comprising a curved transverse web, the two webs having their concave sides facing each other; and ratchet means for freely extending the length of the first and second slats and resisting contraction thereof comprising a plurality of teeth spaced along the length near the center part of the concave side of one web and pawl means comprising at least one tooth near the center part of the concave side of the other web for engaging the ratchet teeth for substantially free lengthwise extension and restricted lengthwise contraction.
 2. A surgical retractor as defined in claim 1 wherein one of the side pieces comprises a pair of opposed hook-like flanges extending lengthwise along the side edges on the concave side of the lip and wherein the web of the other side piece fits between the flanges.
 3. A surgical retractor as defined in claim 1 wherein each of the side slats includes a pair of spaced apart ribs extending along the length thereof for forming a channel for receiving tissue adjacent a surgical incision or the like.
 4. A surgical retractor comprising: a first elongated elastic slat; a second elongated elastic slat facing the first slat; ratchet means for freely extending the length of the first and second slats and resisting contraction thereof; a pivot for connecting each end of the first slat to the respective end of the second slat with mutual divergence of the two slats at each end so that the slats elastically bow in mutually spaced apart arcuate paths between their ends with the concave sides of the slats facing each other; and ratchet means for permitting the slats to pivot away from each other and restricting pivoting towards each other.
 5. A surgical retractor comprising: a first elongated elastic slat; a second elongated elastic slat facing the first slat; ratchet means for freely extending the length of the firSt and second slats and resisting contraction thereof; a pivot connecting each end of the first slat to the respective end of the second slat with mutual divergence of the two slats at each end so that the slats elastically bow in mutually spaced apart arcuate paths between their ends with the concave sides of the slats facing each other; and ratchet means for permitting the slats to pivot away from each other and restricting pivoting towards each other; and wherein each pivot comprises; a first hinge half integral with one slat; a second hinge half integral with the other slat; and a pin for interconnecting the two hinge halves in pivoting engagement; and wherein the ratchet means comprises: an annular array of radially extending ratchet teeth on the face of one hinge half; and a tooth engaging pawl on the other hinge half.
 6. A surgical retractor comprising: a first elongated elastically bendable slat; a second elongated elastically bendable slat facing the first slat; pivot means connecting each end of the first slat to the respective end of the second slat for pivoting the slats between a contracted position with the faces of the slats in relatively close proximity and an expanded position with the faces of the slats relatively spaced apart; and ratchet means associated with each pivot means for permitting the slats to pivot away from each other and restricting pivoting towards each other so that the slats elastically bow in mutually spaced apart arcuate paths between their ends with the concave sides of the slats facing each other.
 7. A surgical retractor as defined in claim 6 wherein each ratchet means comprises: an annular array of ratchet teeth connected to one slat and extending at least part way around the pivot means; a pawl connected to the other slat and engaging the ratchet teeth; and means for disengaging the pawl from the teeth for permitting the slats to pivot towards each other.
 8. A surgical retractor as defined in claim 6 wherein each of the elastic side slats is freely extensible in a longitudinal direction and includes means for limiting contraction in a lengthwise direction independent of the angle of the pivot.
 9. A surgical retractor as defined in claim 8 wherein each of the elastic side slats comprises: a female member connected to one pivot means; a male member connected to the other pivot means and inserted into the female member, said male member being substantially free to withdraw from the female member in a longitudinal direction and being restricted from further insertion in the female member.
 10. A surgical retractor as defined in claim 9 wherein the male and female members each include a bowed transverse web with respective concave faces thereof facing each other and interengaging ratchet means on the webs for permitting extension and limiting contraction and arranged so that further bowing of the webs disengages the ratchet means.
 11. A surgical retractor comprising: a first arm; a second arm; first pivot means for pivotally interconnecting the first and second arms at one end; first ratchet means for permitting the arms to pivot away from each other and restrict pivoting of the arms towards each other; a third arm connected as an extension of the first arm away from the first ratchet means; means for freely extending the combined length of the first and third arms and resisting contraction of the combined length thereof; a fourth arm connected as an extension of the second arm away from the first ratchet means; means for freely extending the combined length of the second and fourth arms and resisting contraction of the combined length thereof; second pivot means for pivotally interconnecting the third and fourth arms at the ends thereof opposite from the first and second arms respectively; and second ratchet means for permitting the third and fourth arms to pivot away from each other and inhibIt pivoting of the third and fourth arms towards each other.
 12. A surgical retractor as defined in claim 11 wherein each of the arms is elastically bendable in a plane transverse to the axes of the pivot means. 